are given a string num, representing a large integer. Return the largest-valued odd integer (as a string) that is a non-empty substring of num, or an empty string “” if no odd integer exists.
A substring is a contiguous sequence of characters within a string.
Example 1:
Input: num = “52”
Output: “5”
Explanation: The only non-empty substrings are “5”, “2”, and “52”. “5” is the only odd number.
Example 2:
Input: num = “4206”
Output: “”
Explanation: There are no odd numbers in “4206”.
Example 3:
Input: num = “35427”
Output: “35427”
Explanation: “35427” is already an odd number.
Constraints:
1 <= num.length <= 105
num only consists of digits and does not contain any leading zeros.Flow Diagram: –
Solution: –
class Solution {
public String largestOddNumber(String num) {
int oddIdx = -1;
for(int i = num.length() - 1 ;i >= 0 ;i--){
int digit = num.charAt(i)-'0';
if(digit % 2 != 0){
oddIdx = i;
break;
}
}
if(oddIdx == -1) return "";
StringBuilder ans = new StringBuilder();
for(int i = oddIdx ;i >= 0 ;i--){
ans.append(num.charAt(i));
}
ans.reverse();
return ans.toString();
}
}